Treating small home bedroom for production

[audiomutt]

Hi guys. I've been on this forum on and off a bit over the years as I was browsing for info. This site was a little overwhelming with all the details so I would never stay for long. But now that I'm no longer in a pro studio and actually need to create my own space, I've found there is just a ton of junk out there and I'm not sure which data in my brain is accurate anymore and after spending some time researching on here I thought maybe I could jump in the pool as well. Now that I'm doing it, kinda intimidating...

PURPOSE - First I guess, a little about what I'll be doing. I mainly produce commercials and do some light post-prod work. I also do voice work and occasionally I'll play around with music (midi controllers - no talent with "real" instruments).

LOUDNESS - I usually mix right around 70 dbc. As I'm typing up this post, we're getting a pretty heavy rain and the measurement at my window is 49 dbc. It is louder than the cicadas I normally hear or my neighbours (whom I have yet to hear).

ROOM - The room has no treatment currently. Its an odd shape but essentially its about 3,4m x 3,2m x 3,4m. I have my desk, monitors, apollo twin and pc (and some HD650s I mostly use since the room sucks). My exterior wall (with window) is cylinder block, then metal studs and drywall on top. The other walls are single frame with metal studs. The floor is currently concrete with carpet. Behind the little closet is my kitchen. On the side with the short wall and door is a bathroom (rarely used). My neighbours house is about 9m away with a 2,5m fence right between us.

I am using Adam A5x. They are mounted to arms on the desk. Its an adjustable height desk (back pain when sitting too long) so I need the monitors to move with it (I think). They are properly aligned vertically, however they are 1,2m apart from each other and 1m away from my listening position. I'm doing my best to follow the 38% rule.

BUDGET - I'm on a limited budget currently (about $3k max) due to just making the move, but in a few months I should have a stronger cash flow to play around with. I do have to work in the room daily still.

GOAL - I realise with the size/shape of my room I'll be limited in the results I'll be able to achieve. I'm not trying to iso the entire room but do need a good listening environment, also I do need somewhere I can voice so I thought maybe a little vocal booth.

THE PLAN (MAYBE?) -

1) My ceiling is rather high so I'll need a cloud.

2) Traps behind the monitors and one by the back closet wall. Also, adding one for the door. With such a high ceiling I was thinking I would add a track into the wall and then put the trap on a pulley attached to track that I could lower when I closed the door (good idea or dumb idea?)

3) 4" Broadband absorbers on the side walls

4) No plans for diffusion currently

5) Vocal booth in the back closet?


Attached here is the REW test (ughh). Also a sketch of the existing room and the initial idea. So for the questions.

1) As much as I enjoy it, I probably need to get rid of the ceiling fan don't I?

2) I'm slightly lost on bass traps. I've read both more dense/less dense is better. So for clarity.... for bass traps is it better to have 128 kg/m³ (Rockboard 80) or better to have 96 kg/m³ (rockboard 60) or better to have 64 kg/m³ (rockboard 40)... or....?

3) There is a rough idea for a vocal booth in the current closet. Is that a bad idea, is there a better way?

4) Instead of adding the hanging traps in the front corners would it be better to do an inside-out wall? I saw an example in Funkys studio where he had a few similar dimensions that maybe I could adopt.

5) Am I so far off base I need to dive back into the forums and start again? I' not even sure I'm asking the correct questions.

I appreciate the forum allowing me to lurk and learn a few tidbits. If you can provide thoughts I appreciate that as well. Thanks!


Also did the REW test using Stuart's guide. I think it did it correct. I put the REW file in drive - https://drive.google.com/open?id=1M-x5l ... g8SfMS5E7r

[Gregwor]

Welcome! I'm glad you took the leap!

Its an odd shape but essentially its about 3,4m x 3,2m x 3,4m.

As you probably already know, this is not ideal. Your dimensions are all almost identical. This is pretty much a cube which is as bad as it can get. To make things worse, you're at about half the floor space recommended for a good mixing room. Ideally, tracking rooms are larger than mixing rooms. Your cubic dimensions cause a lot of coincident frequencies which is probably why your ~100Hz rings forever in your measurements. Also probably why your ~120Hz shows a deep null. The only way you can improve this is with a ton of insulation.

The floor is currently concrete with carpet.

Rip out your carpet.

I am using Adam A5x. They are mounted to arms on the desk. Its an adjustable height desk (back pain when sitting too long) so I need the monitors to move with it (I think). They are properly aligned vertically, however they are 1,2m apart from each other and 1m away from my listening position. I'm doing my best to follow the 38% rule.

I understand your sitting and standing dilemma but I personally don't have a solution for that as your speakers need to be on rigid stands. Also, according to your picture, you have them out a fair distance from your wall. Having them far from the wall will cause low frequency problems due to SBIR. You need them pushed up against your front wall pretty much touching a 4" chunk of 703 in order to improve that problem.

GOAL - I realise with the size/shape of my room I'll be limited in the results I'll be able to achieve.

Very limited, yes. But it can be drastically improved from the state it's in.

I'm not trying to iso the entire room but do need a good listening environment, also I do need somewhere I can voice so I thought maybe a little vocal booth.

You either ISO the entire room, or not at all. That's the way it works. Your closet is tiny and will sound horrible. In my opinion, your best bet is to use the current room for both mixing and tracking.

1) My ceiling is rather high so I'll need a cloud.

The fact that your ceiling is high isn't the reason you need a cloud. The cloud is needed to acoustically treat your room no matter how high the ceiling is.

2) Traps behind the monitors and one by the back closet wall. Also, adding one for the door. With such a high ceiling I was thinking I would add a track into the wall and then put the trap on a pulley attached to track that I could lower when I closed the door (good idea or dumb idea?)

In your room, you'll need bass traps in as many corners as you can fit them and as big as you can make them. Even with your door eating up some corners, you still have 12 available in your room.

3) There is a rough idea for a vocal booth in the current closet. Is that a bad idea, is there a better way?

I think that's a bad idea. I'd toy with the idea of taking off the doors which would give you more area and help with your modal distribution. Also, you could damned near stuff that whole thing full of hangers/insulation.

4) Instead of adding the hanging traps in the front corners would it be better to do an inside-out wall? I saw an example in Funkys studio where he had a few similar dimensions that maybe I could adopt.

No. An inside out wall is used in the construction of your inner leaf when you are building a two leaf MSM system. It really has nothing to do with acoustic treatment. Also, you shouldn't ever hang your bass traps. They should go floor to ceiling. The bigger the better. And, when they do go floor to ceiling, you are effectively treating the trihedral corners which is the most effect spot for bass trapping!

5) Am I so far off base I need to dive back into the forums and start again? I' not even sure I'm asking the correct questions.

I'd suggest reading through

www.roletech.net/books/HandbookAcoustics.pdf

After you read that, you should be pretty much ready to treat your room. This forum has a lot of great info on things like silencer boxes and in depth HVAC design/calculations. Things that the book above only touches on. Also, this forum has a lot of in depth info regarding things like construction of windows, doors, electrical, soffit mounting speakers, Sorbothane calculations, general construction for ceilings and walls using John Sayer's inside out technique as well as things like fire blocking, vapour barrier, concrete and foundation, and general material suggestions and data. I'm sure there's a lot more I didn't mention. But, as you get deeper into your design, you can just use the search function and find some threads that will answer your questions and cause you to ask yourself more!

Keep us posted and feel free to ask more questions!

Greg

[Soundman2020]

Hi there " audiomutt", and Welcome to the forum!

In many of my comments below, I'm just repeating what Greg already said, or adding some more details to it.

I've found there is just a ton of junk out there and I'm not sure which data in my brain is accurate anymore and after spending some time researching on here I thought maybe I could jump in the pool as well.

That's what the forum is all about: trying to dispel the bad myths and untruths about acoustics, and leave you with only the true good stuff.

From what you said about purpose and loudness, it seems that you aren't very loud: that's good, as it makes the isolation simpler. However, you did also mention rain noise coming in at about 50 dB, and cicadas being loud too, so you it seem that you do need some isolation.

its about 3,4m x 3,2m x 3,4m.

As Greg mentioned, that's a rather unfortunate set of dimensions, since they are all practically the same. That's the reason for your massive modal peaks at about 100 Hz and 150 Hz, and the smaller one around 53 Hz. Those are your first, second, and third order axial modes, which pretty much line up in all three directions:

AudioMutt--REW-WF--modal.png

There's also a lot of low-end "mud" in your room, which is low frequency background noise getting in. That's due to the lack of isolation.

But the room is what it is, and it's better than having no room at all!

There's not much you can do about the dimensions: You could make lower the ceiling a bit, but that would reduce the room volume, which is already small, so I would not recommend that. Instead, use some of that space for massive bass trapping.

My exterior wall (with window) is cylinder block,

I think you mean "cinder block", not "cylinder block"! Autocorrect, maybe?

The floor is currently concrete with carpet.

Concrete slab = good. Carpet = bad. Get rid of the carpet.

They are mounted to arms on the desk.

Forget that. Mount them on speaker stands of the correct height, pushed up tight against the front wall of the room, except for a 10cm gap where you will need treatment. Arm-mounted speakers are not a good idea, for several reasons, and speakers should also not be over the desk, or attached to the desk.

so I need the monitors to move with it (I think)

Nope! You need them to be at a fixed height, which does not change. The "standard" height is 120 cm, which is about 47 1/4", but you can go a bit higher if necessary. Thats the height of the ACOUSTIC AXIS of your speaker, NOT the height of the top or bottom of the speaker cabinet.

They are properly aligned vertically,

So you already have them both set at exactly 120cm above the floor?

however they are 1,2m apart from each other and 1m away from my listening position.

That's about right, given the dimensions of your room. They could be a bit further apart, maybe 140 cm. But once again, we are talking about the ACOUSTIC AXIS of your speakers, not the sides of the boxes.

I'm doing my best to follow the 38% rule.

The 38% "rule" would put your head about 130 cm from the front wall, so I can't see how your ears would then be only 100 cm away from your speakers, unless the speakers are very large...

Also, that "rule" is not really a rule at all: it's a guideline. A starting point. In most of the rooms I design, the mix position ends up a bit forward from there, a few cm closer to the front wall.

also I do need somewhere I can voice so I thought maybe a little vocal booth.

There's no space for that. The room is already too small to be able to take off more of it. I would just isolate the room enough so that you can do your vocal stuff right there, in the room. It is very possible to track vocals in a control room, as long as the isolation is good enough.

1) My ceiling is rather high so I'll need a cloud.

You'll need a cloud ANYWAY, regardless of the ceiling height! I would use a large portion of that ceiling space for deep bass trapping at the front of the room, then hang the ceiling cloud below that. Make large, angled, and hard-backed.

2) Traps behind the monitors and one by the back closet wall

Your bass trapping needs to go in the CORNERS, not against the walls. You need absorption panels on the walls, yes, but the trapping goes in the corners. In your case, ALL of the corners that you can possible get it in (there are twelve in a room...), and deep.

With such a high ceiling I was thinking I would add a track into the wall and then put the trap on a pulley attached to track that I could lower when I closed the door (good idea or dumb idea?)

It might work, but I would go with something simpler, attached to the back of the door permanently, or maybe on wheels.

3) 4" Broadband absorbers on the side walls

Probably, but first do the basic treatment, then decide on that.

4) No plans for diffusion currently

Room is too small for numeric-based diffusion.

5) Vocal booth in the back closet?

I would use the closet for more bass trapping! Take off the doors, leave it open, and fill it with hangers in the part behind the doors, and stacked insulation in the sides (beyond the edges of the doors).

1) As much as I enjoy it, I probably need to get rid of the ceiling fan don't I?

Right! That has to go.

2) I'm slightly lost on bass traps. I've read both more dense/less dense is better.

That's one of those myths that is circulating still: it SEEMS right, intuitively, that big deep bass waves would need heavy, dense insulation to treat them. But it is not true. A lot of stuff about acoustics is not intuitive, because we can't see sound with our eyes, so we assume it must behave in certain ways. If we COULD see it, then it would be a lot easier to understand. I could go into all the technical details of why you actually need lighter stuff for bass trapping, and heavier for the top end of the spectrum, but just look at the specs for the OC-700 line, and you'll see it for yourself: OC-701, the lightest one (lowest density) has better performance for low frequencies that OC-703, which is more dense but still good, and OC-705 (the heaviest) is worse than both of the others.

There is an optimal density for each frequency range and each type of insulation. If you are using mineral wool insulation, then you would need a density of something like 40 kg/m3, but if you are using fiberglass insulation, it needs to be more like around 20 kg/m3.

In fact, it's not actually the density or weight that matters, but something called "gas flow resistivity", which is measured in the obscure units of "MKS rayls", which can also be written as "Pa.s/m2" (or "Pascal seconds per square meter" if you want it in words! ), and you need something around 3,000 rayls for thick, deep, bass trapping.

Here's a couple of simplified graphs that should help you grasp this a bit better:

porous-absorption-graphs--4--GFR--3k-6k-9k-12k--500mm--normal.jpg

That's for normally incident sound, and it shows the coefficients of absorption for four different densities. I set those at 3000 rayls (blue), 6000 rayls (green), 9000 rayls (red) and 12000 rayls (yellow). You can clearly see that the higher densities are not so good for lows. It's hard to translate "rayls" to actually density of the insulation, but VERY roughly you could estimate those as perhaps 19 kg/m3, 21 kg/m3, 23 kg/m3, and 26 kg/m3, but do not take that as Gospel truth! Just very rough estimates. It's different for different products, manufactures, processes, etc.

The above is for NORMAL incidence, which exagerates the effect, and isn't realistic. Here's the same graphs, but for randomly incident sound:

porous-absorption-graphs--4--GFR--3k-6k-9k-12k--500mm--random.jpg

You can see that there's less variation there, and the green curve (6000 rayls) would probably be the best for you. But there's not much in it, so don't sweat it too much: Anything around 20 kg/m3, give or take, is going to work fine. 15 kg/m3 to 25 kg/m3 would be just great.

for bass traps is it better to have 128 kg/m³ (Rockboard 80) or better to have 96 kg/m³ (rockboard 60) or better to have 64 kg/m³ (rockboard 40)... or....?

Of those, the Rockboard 40 is closest to what you need, but still rather dense. It's not just about the absolute density by itself, but also about the thickness. 4" if that hat might be fine for a wall panel, but for the large thicknesses you need in deep bass trapping, I would suggest something lighter. Maybe around 40 kg/m3, if you can get it (assuming you want to stick to mineral wool, not fiberglass).

3) There is a rough idea for a vocal booth in the current closet. Is that a bad idea, is there a better way?

Bad idea: just track your vocals in the same room.

4) Instead of adding the hanging traps in the front corners would it be better to do an inside-out wall? I saw an example in Funkys studio where he had a few similar dimensions that maybe I could adopt.

Are planning to isolate your room now? You said you were on a tight budget, so I assumed you would not be isolating at this stage: just treating. But if you do want to isolate as well, and have the extra budget to do that, then yes, inside-out walls are an option. Take a look at this room, which we are tuning right now: it is all inside-out, all over (all walls and ceiling ): http://www.johnlsayers.com/phpBB2/viewt ... =2&t=21368 You can see how that is turning out. That is a similar size to your room, so compare the initial graphs we had there, with the ones you have for your room...

But if you are NOT planning on isolating your room at this stage, then there's no point in building a wall there!

Also did the REW test using Stuart's guide. I think it did it correct.

I'm not s sure you did it correctly! All three graphs appear to be at the same level.... that cannot happen in real life. If you have two speakers playing together, the TOTAL sound must be louder than just one playing on it's own. So the "LR" graph (both speakers at once) should be 6 dB higher than the "L" and "R" independently. Even if your speakers are very badly matched, and set up very badly there would still be an increase of at least 3 dB.... But there's no increase at all... I suspect that you re-calibrated the system before doing the "LR" test. You only ever calibrate the system, ONCE, then you never touch that again.

But apart form that, the data looks valid. It shows pretty much what I'd expect for that room.

Actual photos of the room would help.


- Stuart -

[audiomutt]

Greg and Stuart - thanks! Been in the middle of trying to finish this move and travel for work. I have read these replys over and over and it has caused me to go back and do more research. Before I post any more that showcases my lack of knowledge I'm going to seek out some answers in the forums and develop a solid plan. Only things I know I'm doing for sure now are:
1) Rip out carpet,
2) No vocal booth in rear of room,
3) Soffit mount speakers,
4) Steve-O the ceiling fan (https://www.youtube.com/watch?v=uPkf6DTG8wQ)
5) Keep reading acoustics handbook (but not on cell, too damn small),
6) Dive back in to the forums to look for the goodies

Stuart, read your post(s) on how nearfield speakers are marketing talk. Whew, I shared that one around.

Just wanted to say a quick thanks to you both for the time.

-Chris

[Gregwor]

6) Dive back in to the forums to look for the goodies

Just like your first picture shows -- 15 John Sayer's Forum tabs open on your internet browser hahaha Good work!

Greg

[audiomutt]

After salivating over Frank's room for the past 2 weeks, I think I might take the plunge and attempt to do this right. Reading through the forums I'm not the first that was going to start down one path and then change gears so I'm sure this comes as no surprise. I've practically lived in the 29 pages of Frank's room for days now, but I've also visited Martin's room a bit, as well as Gareth's, Matt's and plenty of others.

As much as I feel like I'm getting this, I'm discovering that one small tweak on paper can change 10+ other things, one small tweak in sketchup changes enough to make me put my head in the wall, and I'm going to assume tweaks in real life might affect enough that I'll be ready to sell this place before I'm done.

You either ISO the entire room, or not at all. That's the way it works. Your closet is tiny and will sound horrible. In my opinion, your best bet is to use the current room for both mixing and tracking.

Okay, working on a plan for the whole room

I think that's a bad idea. I'd toy with the idea of taking off the doors which would give you more area and help with your modal distribution. Also, you could damned near stuff that whole thing full of hangers/insulation.

How about tossing the doors and taking down the wall to free up more space (as shown in new sketchup drawings)? Or does it matter just as long as its stuffed like a Thanksgiving turkey?

I understand your sitting and standing dilemma but I personally don't have a solution for that as your speakers need to be on rigid stands. Also, according to your picture, you have them out a fair distance from your wall. Having them far from the wall will cause low frequency problems due to SBIR. You need them pushed up against your front wall pretty much touching a 4" chunk of 703 in order to improve that problem.

Okay, soffit mount monitors. Plan is to sit/stand/dance as much as I need, and then return desk to primary position for critical listening.

No. An inside out wall is used in the construction of your inner leaf when you are building a two leaf MSM system. It really has nothing to do with acoustic treatment. Also, you shouldn't ever hang your bass traps. They should go floor to ceiling. The bigger the better. And, when they do go floor to ceiling, you are effectively treating the trihedral corners which is the most effect spot for bass trapping!

Okay, ceiling to floor then... You mention trihedral corners. Should I angle the corners at the top toward centre of the room? The front soffit boxes I have in the drawing goes up 2,5m should I extend it all the way up or work on making it solid (as I mention further down in the post)?

From what you said about purpose and loudness, it seems that you aren't very loud: that's good, as it makes the isolation simpler. However, you did also mention rain noise coming in at about 50 dB, and cicadas being loud too, so you it seem that you do need some isolation.

And lately non-stop mowers

But the room is what it is, and it's better than having no room at all!

I've been complaining a little to my wife. Going from nice studios to this has been a challenge, but that comment put me in my place

My exterior wall (with window) is cylinder block,

I think you mean "cinder block", not "cylinder block"! Autocorrect, maybe?

Yep, but with the mowers lately the accuracy of the statement sounds not too far off!

Forget that. Mount them on speaker stands of the correct height, pushed up tight against the front wall of the room, except for a 10cm gap where you will need treatment. Arm-mounted speakers are not a good idea, for several reasons, and speakers should also not be over the desk, or attached to the desk.
You need them to be at a fixed height, which does not change. The "standard" height is 120 cm, which is about 47 1/4", but you can go a bit higher if necessary. Thats the height of the ACOUSTIC AXIS of your speaker, NOT the height of the top or bottom of the speaker cabinet.

Roger - 120 cm on acoustic axis it is, and (hopefully) soffit mounted

That's about right, given the dimensions of your room. They could be a bit further apart, maybe 140 cm. But once again, we are talking about the ACOUSTIC AXIS of your speakers, not the sides of the boxes.

Measurements are slightly different after playing around with ideas in sketchup. 161cm apart, 141 cm from listening position. That puts me at 173 cm into the room and 266 cm from the back wall (with closet removed). Not sure how to factor in my angled wall. Would these still be okay? Also, thinking I'm going to have to lose my dual monitors. One larger one with a smaller footprint should do the trick I think.

It is very possible to track vocals in a control room, as long as the isolation is good enough.

Its how I've done it for 6 years now. Not sure why I was sold on trying to do a VO booth... bought in the "hype" as they say. VO Booth idea is scrapped

You'll need a cloud ANYWAY, regardless of the ceiling height! I would use a large portion of that ceiling space for deep bass trapping at the front of the room, then hang the ceiling cloud below that. Make large, angled, and hard-backed.

You and Greg both got me there. Working out best way to pack it in. Thinking if I extend the frame of the soffit up higher I can create the support I need to run 2x4s across the front and over the window area back to the mix position.

There is an optimal density for each frequency range and each type of insulation. If you are using mineral wool insulation, then you would need a density of something like 40 kg/m3, but if you are using fiberglass insulation, it needs to be more like around 20 kg/m3. In fact, it's not actually the density or weight that matters, but something called "gas flow resistivity", which is measured in the obscure units of "MKS rayls", which can also be written as "Pa.s/m2" (or "Pascal seconds per square meter" if you want it in words! ), and you need something around 3,000 rayls for thick, deep, bass trapping.

Yeah.... so this was definitely not covered in Magic Schoolbus. Wow... did you know the guy that discovered rayl (John William Strutt, 3rd Baron Rayleigh) also discovered the phenomenon to explain why the sky is blue. Thanks for the explanation and the graphs. I've read you mention elsewhere that the pink stuff is hard to stack. I think I'll stick with Safe N Sound which is 40 kg/m3 (and a favorite on the forum is seems).


Things I'm still working on:

- Still studying Master Handbook of Acoustics. I'm interested, but after a long day it can be a little dry.

- I haven't read up on what to do about the window just yet (more "small" tweaks coming to plan) and also the door. I have a hollow core door currently so I'll need to figure that out.

- Not sure best way to proceed on ceiling just yet. Looking into the forums.

- Franks room looks like the ceiling is packed with rockwool. I know he had similar dimensions, I'm thinking I need to figure out a plan to make this happen. Just haven't found one that make most sense yet.

Questions (If I may):

1) Would it be advisable to build one big hanger on the back wall, or better to just stack safe n sound across the back?

2) Is there a good thread on how to find the angle of incidence and adjust in sketchup? I havne't had much success in my search. I did steal Martin's design for ray tracing... just now sure how to finish it.

3) Should hangers go all the way across the top and bottom in the soffit box or should I keep it like it is in the drawing and fill the rest with loose insulation?

4) Are there questions I should be asking but am not?

Thanks in advance for any guidance. Off to bed for me, see ya.

[Gregwor]

Hey Chris,

How about tossing the doors and taking down the wall to free up more space (as shown in new sketchup drawings)? Or does it matter just as long as its stuffed like a Thanksgiving turkey?

Removing it would help with unwanted specular reflections, for sure!

Okay, ceiling to floor then... You mention trihedral corners. Should I angle the corners at the top toward centre of the room?

The deeper the insulation is in the corners, the better. But, chances are, your already going to have your corner traps 3 feet wide, so that's pretty dang good. Adding the angle at the top sure would make the build more difficult.

The front soffit boxes I have in the drawing goes up 2,5m should I extend it all the way up or work on making it solid (as I mention further down in the post)?

Make the "baffle" go at least as high as your cloud front will drop. You won't be able to determine that height until you design your cloud. Everything is a juggling act with the design process hey!??? And to think people are building their studios from the ground up without a 3D model!

Yep, but with the mowers lately the accuracy of the statement sounds not too far off!

Hey Mr. Florida, complain about mowers all you want. I'll have snow blowers disturbing me very shortly here! Nice weather the last two days (sunny t-shirt weather and able to take my kids out for bike rides), but a few days prior, we had 6" of snow on the ground!

Not sure how to factor in my angled wall. Would these still be okay?

Just need lots of treatment on the corner wall! It's 2:24am here right now so I'm too tired to check your measurements. Check the ITU-R BS.1116-3 to see if your measurements line up with their recommendations

Also, thinking I'm going to have to lose my dual monitors. One larger one with a smaller footprint should do the trick I think.

You could build a custom desk (maybe modify one) that is sloped towards you and embed the monitors in the top of it.

You and Greg both got me there. Working out best way to pack it in. Thinking if I extend the frame of the soffit up higher I can create the support I need to run 2x4s across the front and over the window area back to the mix position.

Read this thread. The clouds he made are gnarly. Might give you some ideas!
http://www.johnlsayers.com/phpBB2/viewt ... &start=285

I've read you mention elsewhere that the pink stuff is hard to stack. I think I'll stick with Safe N Sound which is 40 kg/m3 (and a favorite on the forum is seems).

It's great for in walls though! And also works great for across the backs of the slats in Helmholtz devices! It's super cheap compared to the alternatives too.

Still studying Master Handbook of Acoustics. I'm interested, but after a long day it can be a little dry.

I'm a slow reader, so it took me a long time to get through. Not that I didn't understand it, but just reading in general sucks for me. Just do a page or two at at time even. Before you know it, you'll be done. And, the last bit of the book is nothing (glossary and such). Be sure to read the software section even though we use REW here and it isn't covered in the book. The principles still apply!

I haven't read up on what to do about the window just yet (more "small" tweaks coming to plan) and also the door. I have a hollow core door currently so I'll need to figure that out.

I'll share my google drive windows and doors notes for you if you'd like.

Franks room looks like the ceiling is packed with rockwool. I know he had similar dimensions, I'm thinking I need to figure out a plan to make this happen. Just haven't found one that make most sense yet.

That's because his ceiling was built inside out.

1) Would it be advisable to build one big hanger on the back wall, or better to just stack safe n sound across the back?

Frame out a false wall that you can install treatment in/on. Hangers are a forum favorite. Super chunks or hangers in the corners. And like Frank's build, you may have to add plastic or slats over it. Either way, it will look and perform great.

2) Is there a good thread on how to find the angle of incidence and adjust in sketchup? I havne't had much success in my search. I did steal Martin's design for ray tracing... just now sure how to finish it.

Build a ray out of two lines. Select the two lines, hit G and make it a component. From there, you can duplicate the component and use the rotate tool to make a bunch that cover the 5 degree intervals on the horizontal and vertical planes. I personally assigned each to it's own layer so that I can clear up my work area. Add a dotted line with the tape measure at the height of your rays, horizontally. Use the protractor between it and your ray. It will tell you your angle. Duplicate your ray component. Place it's end where it will reflect from and set it's angle (using the protractor) to the exact same angle that you measured previously. Do that for each ray. It doesn't take too long. Then, do the same method with the ceiling clouds. The most annoying part is just redoing it after you adjust a wall or cloud angle!

3) Should hangers go all the way across the top and bottom in the soffit box or should I keep it like it is in the drawing and fill the rest with loose insulation?

All the way across. It would be more effective (for hanger depth) and ease of build to straighten out the hangers and make them parallel to your side walls (check my design thread out -- I was advised to do the same thing)

4) Are there questions I should be asking but am not?

Search the forum for "soffit wings". You'll find that adding these will get you your RFZ 2 foot diameter sphere around your head more easily! Implementing these will also allow you to get nice deep hangers in those front corners (again, check my personal thread).

You're totally on the right track. I'm super impressed with your progress (considering you even had time to work on our TL Calc -- can't wait to complete that and post it on the forum!)

Greg

[audiomutt]

Thanks Greg - By the way... it was a chilly 79 F here today!

Thanks for clarifying the ray-tracing and searching soffit 'wings'. Some pics attached (hoping for some feedback on the ray-tracing). Does it appear to have been done correctly?

Read this thread. The clouds he made are gnarly. Might give you some ideas!
viewtopic.php?f=2&t=14814&hilit=No+problem%2C+Simo&start=285

The Simone room is freaking great. The clouds looked fantastic. bookmarked for future reference gong forward.

Just need lots of treatment on the corner wall! It's 2:24am here right now so I'm too tired to check your measurements. Check the ITU-R BS.1116-3 to see if your measurements line up with their recommendations

I downloaded the pdf. I can't tell if I need a rosetta stone or sleep to figure this out. Going to try sleep first and then go on from there.

It's great for in walls though! And also works great for across the backs of the slats in Helmholtz devices! It's super cheap compared to the alternatives too.

Okay then, the pink stuff isn't out. In my searching the forum I found the link to bobgolds with the master insulation list. I'll pick best stuff for me based on local supply when the time is right.

I'll share my google drive windows and doors notes for you if you'd like.

Yes please! So much reading. If only my 6th grade lit teacher could see me know... I'd show her!

Although I will saw, even after I read something 50 times over and feel like I've got it.... I still catch myself doing the exact thing I know not to do.

So now for the-ray tracing pics.... then going to plow into some of the changes now that I've adjusted the cloud height/angle. Ohhh.... and, am I giving up to much space and making my room too small?

[Gregwor]

Thanks Greg - By the way... it was a chilly 79 F here today!

Ha! That's Hawaii weather dude!

Thanks for clarifying the ray-tracing and searching soffit 'wings'. Some pics attached (hoping for some feedback on the ray-tracing). Does it appear to have been done correctly?

The ray tracing looks perfect!

On the BS.1116-3, read the last few chapters.
Here are some soffit guidelines for placing your speakers. They look quite close to the window edge of the baffles. It might be okay, but just double check that they follow these guidelines:

-The front baffle should be at least 3 times the diameter of the woofer. Ex: 8” woofer would need at least a 24” wide soffit. Wider = better.
-Speaker not centered on soffit. Offset ~⅖ of the width and around ¼ of the height of the baffle. Difference between left and right = 20% at least.
-Speakers between ~28% and 34% width of the room away from the side walls. 25% is BAD! This is a frequency null point! Also don’t put them on the 45 degree line from the corner however put them as far apart as possible.

Yes please! So much reading. If only my 6th grade lit teacher could see me know... I'd show her!

I'll email you that shiz.

So now for the-ray tracing pics.... then going to plow into some of the changes now that I've adjusted the cloud height/angle. Ohhh.... and, am I giving up to much space and making my room too small?

It's just just going to be visually small. Acoustically, it's the same size!

Your RFZ sphere looks killer! Just confirm the speaker placement on the baffles. Worst case, you might have to move them closer to the walls at which point you will have to angle the soffits in more. It should still all work out great!

Greg

[Soundman2020]

So now for the-ray tracing pics.... then going to plow into some of the changes now that I've adjusted the cloud height/angle

Reinforcing what Greg said, To me, it looks like your speakers are getting awfully close to the inner edges of your soffit baffles... You do want a decent area on each side of the speaker, or you'll end up with unbalanced issues. However, you also do NOT want the speakers centered in the baffles... that can potentially create lobing patterns. Centering your speaker somewhere around 2/5 of the width of the baffle is a good place to start, then adjust a bit either way to fit the room better. If necessary, change the angle of the soffit and move the mix position a little. As Greg pointed out, the general rule of thumb is that the baffle width should be 3 times the diameter of the woofer, at least. Bigger is better.

Also, I'm sure you already know that the "38% rule" is not a rule at all! Just a guideline for a good initial position, as you nudge things around in quest of perfection. And I'm sure that you also know that the famous "equilateral triangle with perfect 30° angles" is also not carved in stone: it is entirely permissible to change the angles. Anywhere in the range 20° to 45° toe-in angle is acceptable, but I do try to keep things between 25° and 35° wherever I can.

25% is BAD! This is a frequency null point!

Usually 25% is bad, but it can be useful under some circumstances! Precisely because it is the null point for some room-width modes, it can be useful to position the speakers there to help deal with those modes, if they are predicted to be a problem in the room, and there's no place to treat them effectively. After all, if the speaker is in the modal null, then it cannot possibly trigger that mode! So putting the speakers at 25% can be useful for those cases... provided that you know what you are doing!

Of course we also do tend to always mount our speakers in another modal null, without even thinking about it! The first order height mode. "Standard" speaker mounting height is 120 cm but most people prefer a little higher, maybe 122-125 (around 4 feet). That's the acoustic axis height, and since most house ceilings are 2.44m (8 feet), do the math... That's the exact half-wave point for the vertical axial modes (floor-ceiling modes)... xThat's why you seldom see first-order height modal issues in typical home studios, with typical ceiling heights... The speaker is in the modal null, so it cannot trigger the mode. Even more interesting, since the speaker height is set to be the same as normal seated ear height, it means that we mostly end up sitting in the modal null, as well! So the speaker can't trigger it, and even if it did, we wouldn't hear it... Mind blown...?

So, for some rooms, it might be OK to put the speakers at 25% width, if you are careful.

I try to use every tool in the designer's toolbox to tweak the design, and this is one of those not-very-well-known tools.


- Stuart -

[Gregwor]

Mind blown...?

Everyday Stuart. Everyday!

Greg

[Soundman2020]

Mind blown...?

Everyday Stuart. Everyday!

Greg

Oh, and I forgot to mention, that we also sit on the room center-line, always, because... Symmetry! So first-order room width modes are usually not too much of a problem either....

Now, having said all that, the inverse issue is also true: If you are in the modal null for all first-order modes, then you are automatically in the modal peak for all second-order modes... However, since those are at higher frequencies, they are not so much of a problem, and easier to damp with porous absorption.

Ever wonder why the length axis is always the big issue in small rooms? This is why you generally see all of the lengthwise modes popping up on REW graphs, but only some of the width-wise and height-wise modes...

The point being that, with careful choice of speaker location and mix position location (and possibly even client-couch location), you can use the room to help your modal situation. And with careless choices, you end up with problems....



- Stuart -

[audiomutt]

Hey guys, hope the holidays have been good for you!

I've been beating myself up over this making minor tweaks and then re-tweaking, scrapping it and trying again. But I think I might be making some headway today. I had to move the unit further over and partially cover the existing window (was trying to avoid it, but not possible) to get the monitor at 29% into the room. Then I had to change the angle slightly. Minor tweaks but lots of work to re-do raytracing and getting new angles to line up. I also revised the baffle. The acoustic axis is now sitting in the lower quarter of the baffle pretty close to the recommendations . Think this is looking okay to proceed?

[audiomutt]

i was back in the forums briefly today and realized I'd never followed up here. I did finally complete my room. There are spots where its lacking, but I find it very comfortable to work in and if you find yourself reading this post while on the verge of making a decision, I can say that even with the flaws in my room it was absolutely worth the time and energy.

I haven't done a REW test recently because I know it'll show me issues i'll want to fix and in this moment, ignorance is bliss. I'll wait until the newness has worn off before going down that path.

A few pics of the journey.

[audiomutt]

And of course the last few completed pics.